Heel regulating device for use with sailing simulator



. Oct. 6, 1970 R. s. WADDINGTON ETAL 3,531,375

HEEL REGULATING DEVICE FOR USE WITH SAILING SIMULATOR Filed Dec. 28, 1967 3 Sheets-Sheet 1 flab CED A1. W J/v vfi coia I Attorney 1970 R. s. WADDINGTON ET AL HEEL REGULATING DEVICE FOR USE WITH SAILING SIMULATOR Filed Dec. 28, 1967 3 Sheets-Sheet 2.

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HEEL REGULATING DEVICE FOR USE WITH SAILING SIMULATOR Filed Dec. 28, 1967 s Sheets-Shegt 5 mmv ma 5w 5? 6?? United States Patent 3,531,875 HEEL REGULATING DEVICE FOR USE WITH SAILING SIMULATOR Rogor Strange Waddington and Bruce Duval, Lausanne, Switzerland, assignors to T.P.I. Limited, Nassau,

Bahamas, a company of the Bahamas Filed Dec. 28, 1967, Ser. No. 694,262 Int. Cl. (20% 9/06 U.S. Cl. 3511 11 Claims ABSTRACT OF THE DISCLOSURE With a sailing simulator for teaching a pupil the art of sailing on dry land by instructing him in a stationary hull mounted for rotational movement in response to a tiller and mounted for heeling motion by an actuator to simulate the heeling action of the supposed wind, it is necessary to provide arrangements whereby the heeling actuator is activated to a degree depending upon the strength of the supposed wind and in direction thereof relative to the instantaneous bearing of the craft. This has been achieved by having a skilled operator to activate the actuator in accordance with his experience. In accordance with this invention there is provided a computor device having transducers responsive to supposed wind direction, supposed wind strength and the position of the boom of the simulator relative to the hull. Two of the transducers are linked to provide an output dependent upon the effect of two of the parameters and a third transducer is arranged to modify said output, which modified output is applied to the heeling actuator.

The present invention relates to training devices and is especially concerned with sailing simulators by which a pupil may learn the art of sailing on dry land. Such simulators have a hull and a boom, the latter of which is usually controlled by a rope known as the main sheet held by the pupil, as well as mechanism which causes the hull to rotate in response to movements of a helm, e.g. a tiller, by the pupil.

With such sailing simulators, it is essential that the angle of heel of the hull (i.e., the structure in which the pupil is seated) should respond realistically to the pupils actions as in actual sailing. The angle of heel depends upon the speed of the supposed wind, the direction of the supposed wind relative to the hull or to the boom and the angle of the boom relative to the hull. The direction relative to the hull is, of course, related to the direction relative to the boom in a simple manner which depends upon the angle of the boom relative to the hull. In order to avoid having an instructor constantly present to set the angle of heel to correspond with the conditions, it is advantageous to provide a computor responsive to the three conditions and operable to give an output signal corresponding with the required angle of heel so that the heeling action can be performed by a suitable mechanism such as a servo system.

As will be appreciated the angle of heel should be zero when the supposed wind is astern and the boom let fully out to make a right angle with the fore-aft axis of the hull. Under conditions representing reaching or sailing close hauled there should be an angle of heel which is appropriate to the conditions for an actual sailing vessel under way. For given conditions in actual sailing the angle of heel naturally depends upon the design of the vessel and it is to be assumed hereinafter when reference is made to the angle of heel that the angle is an appropriate one for the general kind of vessels, e.g. racing dinghies, that the pupil will eventually handle on water.

3,531,875. Patented Oct. 6, 1970 In accordance with the present invention there is provided a computor device for computing the angle of heeling of the hull of a sailing simulator having a hull and a boom appropriate to the position of the boom, the speed of the supposed wind and the direction of the supposed wind relative to the simulator, which device comprises three transducers respectively operable to generate a signal representative of the speed of the supposed wind, a signal representative of the direction of the supposed wind relative to the simulator (preferably relative to the boom rather than the hull) and a signal represenative of the position of the boom of the simulator, two of said transducers being linked together to provide a combined output which is variable by the signals from either of said two transducers independently of the signal provided by the other and the third transducer being arranged to provide a heel output signal which is modified by said combined output, the magnitudes and senses of the signals being such that the modified heel output signal has a magnitude and sense appropriate for a sailing craft.

Preferably, the said two of the transducers are operable to generate signals representative of the direction of the supposed wind and the speed of the supposed wind respectively.

It is to be noted that the output of the device, viz the modified heel output signal, is necessarily altered when the signal from any one of the transducers changes. The device is therefore to be contrasted with a device where a signal merely changes the ratio between the effect of two signals without necessarily producing an output. An example of a device of the latter type is a rotary plate Whose angular position represents the supposed wind speed which drives a parallel and coaxial rotary plate via a radially movable ball gripped between the two plates, the radial position of the ball representing the angle of the boom to the wind and rotation of the said parallel and coaxial rotary plate being the output from the device. A change of boom angle to the wind would merely move the ball radially to change the potential output from the device and an actual output would be obtained only when rotation of the first rotary plate occurred to represent a change of wind speed. A change of wind direction unaccompanied by a change of wind speed would produce no change of heel angle even though a change of wind speed would produce a change in the absence of a change of wind direction. The result would be quite useless.

Advantageously a device according to the present invention is provided with a heeling position senser-for generating a signal representative of the angle of heel of the hull and comparator means for generating an error signal from the heeling position senser signal and the modified heel output signal.

The device can be provided in any one of various different forms for example mechanical, electronic or fluid-logic forms. Hereinafter mechanical and electronic forms will be described but it is to be understood that the invention is not to be regarded as limited thereto.

A heeling position senser as referred to hereinbefore can be one input of a differential gear the other input of which is connected with a heeling actuator and the output of which provides the error signal.

One of the said two transducers may be linked to an adjustable throw crank, one of them being arranged to rotate the crank and the other of them being arranged to adjust the throw thereof, the combined output being represented by the movement of a member connected with the arm of the crank. The third transducer may be arranged to adjust the throw of a second adjustable throw crank which is rotatable by the said movement of the said member, and an output member is connected with the arm of the second crank.

The cranks, or one of the cranks, may be of complex construction to facilitate adjustment and manufacture provided that the fundamental features of a crank are retained. For example the first crank may be provided in the form of a body adapted to be rotated by an actuator serving as one of the pair of transducers, a first link pivoted on said body and adapted to be rotated by a further actuator serving as the second of the pair of transducers, and has a second link pivoted on the first link and connected to a sliding rod, the sliding of said rod providing the combined output; whether or not this arrangement is adopted the second crank may be provided in the form of a first link adapted for rotation in accordance with the combined output, a second link pivoted on the first link and adapted for rotation by an actuator serving as the third transducer and a third link pivoted on the second link, a sliding rod connected to the third link providing the modified output. The sliding rod may be connected to an output transmitter for transmitting a heeling signal to the hull.

Alternatively instead of providing a mechanical arrangement based on cranks or otherwise constructed, the device may have an electrical circuit for producing the combined output and modifying the heel output signal by the combined output. The said two of the transducers are, in a preferred construction, rheostats connected together in series; one of the rheostats is preferably constructed to break the circuit when set to its maximum position, said rheostat being employed as the transducer for the speed of the supposed wind.

The third transducer may be a potentiometer. For example the said two of the transducers are rheostats connected together in series and the third transducer is a potentiometer series connected with the rheostats so that the current therethrough depends upon the setting of the rheostats, the output taken from the wiper of the potentiometer being the modified heel output.

In a most preferred arrangement having an electrical computor circuit, the computor device is connected to a reversible heeling actuator for the hull, the device has an amplifier for the modified heel output, and the electrical circuit is provided with a transducer operable to provide a signal corresponding with the heel angle of the hull and an amplifier for this signal, the two amplifiers being arranged to operate the heeling actuator in opposite heeling directions and to terminate heeling motion of the hull of the device when the required angle of heel is reached.

The following description in which reference is made to the accompanying drawings is given in order to illustrate the invention.

In the drawings:

FIG. 1 shows in plan a computor of the mechanical yp FIG. 2 shows an electrical circuit the lower part of which is a computor of the electrical type and the upper part of which is an electrically operated boom actuating device, and

FIG. 3 shows diagrammatically a sailing simulator incorporating the circuit of FIG. 2.

Referring now to FIG. 1 an L-shaped plate 1 is pivotally mounted at 2 on the computor framework (not shown) and has an operating rod 3 which slides in the computor framework at 4 connected to it and to an actuator 5.

A link 6 is pivotally mounted at one end at 7 on the plate 1 and is formed at the other end with a slot 8. A pin 9 engages the slot 8 and is carried on a nut 10 which slides on the plate 1 and embraces a screwed spindle 11 which spindle is mounted on the plate 1 so as to be capable of rotation by an actuator 12, the nut 10 being prevented from turning by plate 1.

A further link 13 is pivotally mounted at one end at 14 on the link so that the distance between pivots 14 and 7 is equal to the distance between pivots 2 and 7.

The other end of link 13 is pivotally connected at 15 to a rod 16 so that the distance between pivots 14 and 15 is equal to the distance between pivots 7 and 14. The rod 16 is mounted in a guide 17 in the computor framework so as to be capable of axial movement and so that the axis of rod 16 produced passes through the axis of pivot 2 produced.

The rod 16 is pivotally connected at 18 to one end of a link 19 which link 19 is pivoted near its center on the computer framework at 20. A link 21 is pivotally mounted on the other end of link 19 at 22 and has connected to it at the end opposite to pivot 22 a cupped rod 23 in which engages a ball on the end of a screwed spindle 24 which rod is adapted for rotation by an actuator 25 in a tapped hole in the computor framework at 26. A tension spring 27 attached to the link 21 and to the computor framework is adapted to keep the cupped rod 23 in close engagement with the ball on the end of the rod 24.

A further link 28 is pivotally mounted at one end at 29 on the link 21 so that the distance between pivots 22 and 29 is equal to the distance between pivots 22 and 20. The other end of the link 28 is pivotally connected at 30 to a rod 31 so that the distance between pivots 30 and 29 is equal to the distance between pivots 22 and 29. The rod 31 is mounted in a guide 32 in the computor framework so as to be capable of axial movement and so that the axis of rod 31 produced passes through the axis of pivot 20 produced. The rod 31 is connected at its other end to a transmitter 33.

The actuator 5 moves the plate 1 about the pivot 2 so that the angle between the line joining pivots 2 and 7 and the axis of the rod 16 produced is equal to the angle through which the helmsman has pulled the boom from the position it would assume if it could respond freely to the wind. The actuator 5 may be controlled from a boom-angle transmitter of any convenient design.

The actuator 12 rotates the screwed spindle 11 by a function of wind speed such rotation displacing the pivot 14 from being immediately over the pivot 2 by an amount dependent on the wind speed.

It will be seen that if both the plate 1 is displaced so that the line between pivots 2 and 7 is not on the axis of the rod 16 produced, and the pivot 14 is displaced from being immediately over the pivot 2, an axial movement will be imparted to rod 16. This movement of rod 16 will be a function of wind speed and direction.

Any movement of rod 16 will rotate link 19 about its pivot 20. Actuator 25, when rotated for wind direction relative to the fore-and-aft axis of the hull, moves the link 21 so that the pivot 29 is displaced from being immediately over pivot 20, and the angle between links 19 and 21 is dependent upon the angle between the direction of the wind and the fore-and-aft axis of the hull.

It will be seen that if both link 19 has been rotated about its pivot 20 so that the line joining pivots 20 and 22 produced is no longer coincident with the axis of the rod 31, and the link 21 has been moved so that the pivot 29 is not immediately above pivot 20, an axial movement will have been imparted to the rod 31. This axial movement will operate the transmitter 33.

It will be seen that the movement of transmitter 33 depends upon the angle fed by actuator 5, the wind speed fed by actuator 12, and the angle between the direction of the wind and the fore-and-aft axis of the hull fed by actuator 25. The transmissions to and constructions of the actuators 5, 12 and 25, and the dimensions of the computor linkages are so arranged that the output from the transmitter 33 is a measure of the angle at which the hull should heel under the conditions fed to the computor.

The transmitter 33 is for example a bidirectional valve or switch mechanism for a hydraulic or electric circuit which controls the main hydraulic power supply for a reversible heeling hydraulic servo unit. Connected with the heeling actuator is one input of a difierential gear, the other input of which is connected with the hull of the trainer. The output of the difierential represents an error signal and the hydraulic or electric circuit is so arranged that the heeling motion ceases when the correct heeling angle is reached and the error signal reduced to zero.

In the electrical arrangement shown in FIG. 2 the boom position part, i.e., the part above chain-dot line B, has a reversible hydraulic actuator 47 which rotates the mast M in either direction and so swings the boom B which is rigidly attached thereto. The angular position of the mast and boom are applied via bevel gearing to bevel pinion 43a forming part of a difierential. A magslip receiver 42 driven by a star connection from a magslip transmitter 420 rotates the middle bevel pinion 43b of the diiferential. The output from the differential drives a IOU-ohm potentiometer 44 via an electric clutch 413 and an electric brake 415.

Magslip receiver 420, is supplied with a signal representing the supposed direction of the wind and is fed, for example, from the output of a device for determining said direction as described in our copending application Ser. No. 639,77, filed May 18, 1967, now Pat. No. 3,457,783, issued July 29, 1969, said device driving magslip transmitter 420a.

Potentiometer 44 is fed from a 12 volts DC. power supply bridged by two 50 ohm resistors 416a in series, the position at which they connect together being joined to another pair of 50-ohm resistors 41Gb. In parallel with the resistors 41611 is a second pair of SO-ohm resistors the interconnection of which is joined to the input 45 of a D.C. amplifier system 46. This arrangement of resistors ensures that when the potentiometer 44 is in its central position, the signal supplied to the other input to the amplifier via line 417 is identical with the reference input from the said second pair of SO-ohm resistors.

The amplifier system 46 is in the form of two similar amplifiers and the two outputs are applied to an electrically controlled hydraulic servo valve 48 which passes hydraulic fluid in one direction or the other, which depends upon the position of the wiper of potentiometer 44 relative to its mid point and so upon the degree and direction of imbalance of the amplifiers.

Connected across the outputs via a 50-ohm series resistance are two large electrolytic capacitors arranged in parallel with the negative pole of one connected with the positive pole of the other. This arrangement is superior to connecting the negative poles together and the positive poles together. The effect of the capacitors is to prevent unduly rapid movement of the boom.

Any imbalance results in the actuator 47, operated from a hydraulic supply via the servo valve 48, rotating the mast and boom until balance is restored by the differential 43a, 43b, 430 operating upon the potentiometer 44.

When the boom reaches the limit of its travel (in practice the shrouds supporting the mast M) a microswitch 41' release-s the clutch 413 and applies the brake 415 and closes the solenoid valve 418a and via switch unit 41%, opens the valve 41812 in a direction which holds the boom to port or starboard and movement of the boom ceases.

When the relative direction of the wind is such as to move the boom back to another position the microswitch 425 driven from the differential 43a, 43b, 430 by a cam closes the clutch 413 and releases the brake 415, the valve 41% closes and 418a opens and allows the potentiometer 44 to signal the amplifier to cause the boom to follow in the reverse direction.

In order to simulate gybing, i.e., moving the boom suddenly from one side to the other (in for example 0.5 second) the valve 41811 is operated by a switch unit 419a, controlled by the wind resolver system described in our copending application Ser. No. 639,377, filed May 18, 1967, which applies hydraulic pressure to the actuator 47, sending the boom rapidly across the hull. When the boom reaches its extreme position switch unit 41% closes to maintain hydraulic pressure and prevent ready movement of the boom but stops the application of such a hydraulic feed as would tend to move the boom further. The actuator 47 is mounted on bearings .(not shown) and its casing bears a pinion 421 which engages a pair of racks carried by powerful springs. Only one rack 422 and one spring 423 are shown in the drawing. This arrangement allows the pupil to move the boom, as against the force of the wind, by rotating the entire actuator body.

The symbol H used in FIG. 2 represents hydraulic lines. They do not require special explanation.

If the boom were unrestrained by the pupil, it would lie in the same direction as the wind and in actual sailing there would be no forward driving force (unless the boom Were arrested by the shrouds). It is the hauling on the boom by the pupil which sets the boom at an angle to the wind and so produces the required forward driving force.

The pinion 421 on the actuator body drives a second rack and a pinion 421a which is employable for signalling the position of the boom to the potentiometer 51 of the computor part of the circuit shown below the chain-dot line B.

In the computor part of the circuit the angle of displacement of the boom from the position to which the wind would drive it naturally is sensed by the adjustment of a potentiometer 51 linked to the pinion 421a and the angle of heel is sensed similarly by a potentiometer 52. Rheostats 53 and 54 are set to represent the wind direction relative to the fore-and-ait line of the hull and the wind speed. The rheostat 53 is preferably adjusted automatically to correspond with changes in the relative direction as the hull rotates about its vertical axis, e.g., by a device as described in our co-pending application Ser. No. 639,377, filed May 18, 1967, while rheostat 54 may be left set at a constant value or adjusted to simulate changes of wind speed (by an instructor or by a programmed mechanism if provided) such as occur under natural, including gusty conditions. Rheostat 54 is so constructed that in the extreme position which represents no wind the circuit is broken. The output from the potentiometer 51, which is a signal representing the displacement of the boom relative to the position to which it would be driven naturally by the wind is fed to one input of a D.C. amplifier system 56 and the output from the potentiometer 52, which represents the heel angle, 1s fed to a second input to the amplifier. A power pack 55 feeds the amplifier system and the two otentiometers.

The D.C. amplifier system is a transistorized circuit constituted by two identical amplifiers one of which has its input connected with potentiometer 51 and the other of which has its input connected with a potentiometer 52. These inputs may diverge in either direction from the bias level depending upon whether the heeling is over to port or over to starboard and whether the boom is displaced to port or starboard. The outputs of the amplifiers can be identical or either can be greater than the other. The outputs are fed to an electro-hydraulic servo valve 57 having two windings one for each amplifier and two hydraulic outputs 57a and 57b. Which of these out puts is turned on depends upon which of the outputs of the amplifiers is the greater. The hydraulic output is fed to a hydraulic heeling actuator 58 which adjusts the angle of heel and thence the potentiometer 52. The response of the device is thereby fed back to the amplifier system and the parameters of the circuit are so arranged that heeling stops when the appropriate angle is reached.

In order to prevent a violent heeling response, which in extreme cases would throw the pupil out of the hull two capacitors each of 2,000 ,uf., 25-volt electrolytic are connected in series, the two positive sides being joined across the outputs from the amplifier and a 10,000 ,uf. capacitor is connected across the D5. supply to potentiometer 51.

The arrangement whereby the two electrolytic capactors are connected in opposite directions (positive to positive rather than positive to negative) is found to give greatly improved results though no explanation for this phenomenon is offered. The capacitors are not damaged as the voltage across them is trivial.

The appropriate angle of heel depends, besides on the position of the boom, on the wind direction and wind speed. These variables, by adjusting to voltage input to the boom position potentiometer 51 by means of the rheostats 53 and 54, adjust the output from this potentiometer and therefore its input signal to the amplifier 56, thus modifying the output from the amplifier and so affecting the heel angle applied to the hull.

If the supposed wind speed is zero, rheostat 54 is set at its maximum resistance, i.e., infinite. Similarly, the setting of rheostat 53 depends upon the wind direction and the output of the potentiometer 51 to the amplifier 56 therefore depends upon both these factors.

If a supposed significant wind is dead ahead the boom should align itself with the wind and if the wind is dead astern the boom should lie across the fore-aft line of the hull against the shrouds and in neither case should heeling be obtained. Potentiometer 51 gives a neutral output, i.e. an output corresponding with the bias current to its input to the amplifier system. If there is an angle of heel at the time the boom is allowed to go free the outputs to the servo valve 57 operate the heeling actuator 58 and potentiometer 52 to bring the angle to Zero.

If the wind is on the beam or at another angle which should result in heeling and the boom is pulled by the mainsheet into a position where heeling and forward motion should be obtained, the potentiometer 51 produces an output signal which affects the input to the corresponding part of the amplifier system and changes the output thereof in one direction or the other. The output is applied to the heeling actuator 58 via to the servo valve 57 and fed back to the other input of the amplifier via potentiometer 52. The heeling actuator adjusts the angle of heel to the appropriate extent to equalize the two signals from the amplifier when the correct angle of heel is reached.

The SO-ohm resistors 52a and connected in series across potentiometer 52 and 50-ohm resistors 51a and 51b connected in series across the potentiometer 51 have their junction points connected directly together and thus maintained at the same potential. One side of the power supply to potentiometer 52 is grounded and the connection just mentioned prevents the power supply to rheostats 53 and 54 and potentiometer 51 floating and producing spurious results.

If desired, the transistorized amplifiers described hereinbefore may be replaced by vacuum tube or hybrid amplifiers or instead of providing rheostats, potentiometers and electronic amplifiers, their fluid equivalents (fluid logic circuits) may be used. The fluid equivalents lead to little complication as hydraulic lines, from which the fluid may be derived, are present in any case.

It will be understood that a mechanical boom positioner device can be employed with an electronic or fluid logic computor device or vice-versa if desired.

FIG. 3 shows diagrammatically a sailing simulator having a hull 61 rotatable in the horizontal plane about an axis 62 by a tiller 63 connected with a rudder 64 through the medium of a turning motor 65 and a gear box 66 which rotates about a stout shaft 67 secured to a base 68 which rests on the floor 69 of a suitable building.

The hull is also rotatable for a heeling movement about an axis 70 of a shaft 71 driven by gearing 72. The electronic heeling control of FIG. '2 is positioned at 73 and the electronic boom control of FIG. 2 is positioned at 74.

8 Power packs for these electronic controls are located at 74a and 75.

Reference 76 shows a stern sheet which runs through pulley 77 on the boom.

Parts shown also in FIG. 3 are denoted by the same reference numerals or letters as are shown in FIG. 2. A wind resolver direction transducer is shown at 78 for feeding the direction of the supposed wind (which changes as the hull rotates about axis 62) to the rheostat 53. The unit 78 is a device for setting the wind speed, which may be a simple hand control or a programmed device for simulating gusty conditions.

79 is a potentiometer actuated by the tiller for controlling the motor 65.

The parts below the hull 61 are enclosed by suitable panelling. Obviously, various layouts other than that shown may be employed if desired.

We claim:

1. A computor device for generating a heel output signal for regulating the angle of heeling of the hull of a sailing simulator having a hull and a boom and a heeling actuator for imparting heeling motion to said hull, said angle of heeling being appropriate to the position of the boom, to the speed of a supposed wind and to the direction of the supposed wind relative to the simulator, which device comprises three transducers respectively operable to generate a signal representative of the speed of the supposed wind, a signal representative of the direction of the supposed wind relative to the simulator and a signal representative to the position of the boom of the simulator, two of said transducers being linked together to provide a combined output which is variable by the signals from either of said two transducers independently of the signal provided by the other and the third transducer being arranged to provide a heel output signal which is modified by said combined output, the magnitudes and senses of the signals generated by the transducers being such that the modified heel output signal has a magnitude and sense appropriate for the instantaneous conditions of boom position, wind speed, and wind direction with respect to an actual sailing craft.

2. A device according to claim 1 in which the transducer operable to generate a signal representative of the direction of the supposed wind relative to the simulator is arranged to generate a signal representative of the direction of the supposed wind relative to the boom of the simulator.

3. A device according to claim 1 in which there is provided a heeling position senser for generating a heeling position senser signal representative of the heel angle of the hull and comparator means for generating an error signal from the heeling position senser signal and the modified heel output signal.

4. A device according to claim 1 in which the said two of said transducers are operable to generate signals representative of the direction of the supposed wind and the speed of the supposed wind respectively.

5. A device according to claim 1 in which there is provided a rotatable crank and, on the crank, a crank pin movable towards and away from the center of rotation of the crank to give the crank an adjustable throw, and an output member movable by the crank pin, one of the said two of the transducers being arranged to rotate the crank and the other being arranged to move the crank pin and thereby adjust the throw of the crank so that the combined output is represented by movement of the output member.

6. A device according to claim 5 in which there is provided a second rotatable crank arranged for rotation by the movement of the output member, and on the second rotatable crank a crank pin movable towards and away from the center of rotation of the second rotatable crank to give the second rotatable crank an adjustable throw, and a further output member movable by the crank pin of the second rotatable crank, the third transducer being arranged to adjust the throw of the second rotatable crank by movement of the crank pin thereof so that the modified heel output signal is represented by movement of the further output member.

7. A device according to claim 1 having an electrical circuit responsive to the signals of the said two transducers for producing the combined output and being further responsive to the signals of the third transducer for modifying the heel output signal by the combined output.

8. A device according to claim 7 in which the said two of the transducers are rheostats connected together in series.

9. A device according to claim 7 in which the said two of the transducers are rheostats connected together in series and one of the rheostats is constructed to break the circuit when set to its maximum position, said one of the rheostats being employed as the transducer for the speed of the supposed wind.

10. A device according to claim 7 in which the said two of the transducers are rheostats connected together in series and the third transducer is a potentiometer series connected with the rheostats so that the current therethrough depends upon the setting of the rheostats, the

output taken from the wiper of the potentiometer being the modified heel output.

11. A device according to claim 7 having a reversible heeling actuator for the hull connected thereto, an amplifier for the modified heel output, a fourth transducer operable to provide a signal corresponding with the heel angle of the hull and a second amplifier for this signal, the two amplifiers being connected to said heeling actuator and arranged to operate it in opposite heeling directions and to terminate heeling motion of the hull of the device when the required angle of heel is reached.

References Cited UNITED STATES PATENTS 2,208,083 7/1940 Rousseau 3511 2,855,702 10/1958 Taylor 3511 3,305,943 2/1967 Hansen 3511 WILLIAM H. GRIEB, Primary Examiner US. Cl. X.R. 235184 

